χ-separation: Magnetic susceptibility source separation toward iron and myelin mapping in the brain.

Obtaining a histological fingerprint from the in-vivo brain has been a long-standing target of magnetic resonance imaging (MRI). In particular, non-invasive imaging of iron and myelin, which are involved in normal brain functions and are histopathological hallmarks in neurodegenerative diseases, has practical utilities in neuroscience and medicine. Here, we propose a biophysical model that describes the individual contribution of paramagnetic (e.g., iron) and diamagnetic (e.g., myelin) susceptibility sources to the frequency shift and transverse relaxation of MRI signals. Using this model, we develop a method, χ-separation, that generates the voxel-wise distributions of the two sources. The method is validated using computer simulation and phantom experiments, and applied to ex-vivo and in-vivo brains. The results delineate the well-known histological features of iron and myelin in the specimen, healthy volunteers, and multiple sclerosis patients. This new technology may serve as a practical tool for exploring the microstructural information of the brain.

GLP-1 increases preingestive satiation via hypothalamic circuits in mice and humans.

GLP-1 receptor agonists (GLP-1RAs) are effective anti-obesity drugs. However, the precise central mechanisms of GLP-1RAs remain elusive. We administered GLP-1RAs to obese patients and observed heightened sense of preingestive satiation. Analysis of human and mouse brain samples pinpointed GLP-1R neurons in the dorsomedial hypothalamus (DMH) as candidates for encoding preingestive satiation. Optogenetic manipulation of DMHGLP-1R neurons caused satiation. Calcium imaging demonstrated that these neurons are actively involved in encoding preingestive satiation. GLP-1RA administration increased the activity of DMHGLP-1R neurons selectively during eating behavior. We further identified an intricate interplay between DMHGLP-1R neurons and arcuate NPY/AgRP neurons (ARCNPY/AgRP), to regulate food intake. Our findings reveal a hypothalamic mechanism through which GLP-1RAs control preingestive satiation, offering novel neural targets for obesity and metabolic diseases.

The impact of the modified schedules of anatomy education on students' performance and satisfaction: Responding to COVID-19 pandemic in South Korea.

BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic substantially undermined medical education and healthcare systems. Owing to the pandemic in South Korea, most medical schools needed to be flexible when conducting online and offline classes, but the guidelines did not reflect the specificity of medical schools. This study described the impact of modified anatomy education schedules at the Seoul National University College of Medicine (SNUCM) on students' academic performance and satisfaction. METHODS: Anatomy education in SNUCM is divided into three regional units (the upper and lower limbs, trunk, and head and neck). Owing to the COVID-19 pandemic, the schedule was mixed with simultaneous and rotating schedules. The authors conducted exceptions for online lectures, cadaver dissections, and written and practical examinations in three classes of approximately 50 students each. Furthermore, the authors assessed students' performance using three sets of written and practical examinations, and students completed a questionnaire regarding modified anatomy laboratory schedules. RESULTS: Despite the pandemic events in Seoul and South Korea during the laboratory sessions, all sessions were completed without any confirmed COVID-19 cases among the students, faculty, and staff. Most of the scores on the written and practical examinations significantly decreased in 2020 compared to those in 2019. However, in the trunk session that used the virtual anatomy application, the score on the practical examination in 2020 was significantly higher than that in 2019. Over 70% (79 and 77 out of 105 respondents on the upper and lower limbs and trunk, respectively) and 53% (55/105) students reported that there were no significant difficulties in studying anatomy in a face-to-face laboratory. CONCLUSIONS: In conclusion, an adequate education program for cadaver dissection should be developed and provided to overcome the pandemic restrictions. The study findings could serve as a reference for anatomy education during the COVID-19 pandemic.

Proteomic profiling of postmortem prefrontal cortex tissue of suicide completers.

Suicide is a leading cause of death worldwide, presenting a serious public health problem. We aimed to investigate the biological basis of suicide completion using proteomics on postmortem brain tissue. Thirty-six postmortem brain samples (23 suicide completers and 13 controls) were collected. We evaluated the proteomic profile in the prefrontal cortex (Broadmann area 9, 10) using tandem mass tag-based quantification with liquid chromatography-tandem mass spectrometry. Bioinformatics tools were used to elucidate the biological mechanisms related to suicide. Subgroup analysis was conducted to identify common differentially expressed proteins among clinically different groups. Of 9801 proteins identified, 295 were differentially expressed between groups. Suicide completion samples were mostly enriched in the endocannabinoid and apoptotic pathways (CAPNS1, CSNK2B, PTP4A2). Among the differentially expressed proteins, GSTT1 was identified as a potential biomarker among suicide completers with psychiatric disorders. Our findings suggest that the previously under-recognized endocannabinoid system and apoptotic processes are highly involved in suicide.

Bacterial cellulose membrane produced by Acetobacter sp. A10 for burn wound dressing applications.

Bacteria cellulose membranes (BCM) are used for wound dressings, bone grafts, tissue engineering, artificial vessels, and dental implants because of their high tensile strength, crystallinity and water holding ability. In this study, the effects of BCM application for 15 days on healing of burn wounds were investigated based on evaluation of skin regeneration and angiogenesis in burn injury skin of Sprague-Dawley (SD) rats. BCM showed a randomly organized fibrils network, 12.13 MPa tensile strength, 12.53% strain, 17.63% crystallinity, 90.2% gel fraction and 112.14 g × m(2)/h highest water vapor transmission rate (WVTR) although their swelling ratio was enhanced to 350% within 24h. In SD rats with burned skin, the skin severity score was lower in the BCM treated group than the gauze (GZ) group at all time points, while the epidermis and dermis thickness and number of blood vessels was greater in the BCM treated group. Furthermore, a significant decrease in the number of infiltrated mast cells and in vascular endothelial growth factor (VEGF) and angiopoietin-1 (Ang-1) expression was observed in the BCM treated group at day 10 and 15. Moreover, a significant high level in collagen expression was observed in the BCM treated group at day 5 compared with GZ treated group, while low level was detected in the same group at day 10 and 15. However, the level of metabolic enzymes representing liver and kidney toxicity in the serum of BCM treated rats was maintained at levels consistent with GZ treated rats. Overall, BCM may accelerate the process of wound healing in burn injury skin of SD rats through regulation of angiogenesis and connective tissue formation as well as not induce any specific toxicity against the liver and kidney.

Angiotensin II inhibits chemokine CCL5 expression in vascular smooth muscle cells from spontaneously hypertensive rats.

Angiotensin II (Ang II) exerts some of its effects on the vasculature by stimulating chemokines and 12-lipoxygenase (12-LO). In addition, a high expression of chemokines by Ang II has been observed in vascular smooth muscle cells (VSMCs) in spontaneously hypertensive rats (SHR). In this study, the action mechanism of Ang II on CCL5 expression in SHR VSMCs was examined. Expression of CCL5 in SHR thoracic aorta tissues and VSMCs was lower than that in normotensive Wistar-Kyoto rats (WKY) thoracic aorta tissues and VSMCs. Moreover, Ang II inhibited CCL5 expression in SHR VSMCs, but not in WKY VSMCs. Inhibition of CCL5 by Ang II was mediated by both Ang II subtype 1 receptor (AT(1)R) and subtype 2 receptor (AT(2)R) activation in SHR VSMCs. However, Ang II did not inhibit CCL5 expression in SHR VSMCs that were transfected with 12-LO small interfering RNA. In addition, 12-LO metabolite, 12(S)-hydroxyeicosatetraenoic acid (HETE) inhibited CCL5 mRNA expression in SHR VSMCs. The expression of Ang II-induced 12-LO was also blocked by both AT(1)R and AT(2)R inhibitors. Mitogen-activated protein (MAP) kinase, extracellular signal-regulated kinase (ERK)1/2, p38 and Jun N-terminal kinase pathways all mediated the inhibitory action of Ang II on CCL5 expression in SHR VSMCs. Taken together, the inhibitory action of Ang II on CCL5 expression was shown to be mediated by the 12-LO pathway through the activation of both of AT(1)R and AT(2)R and this process was associated with MAP kinase pathways in SHR VSMCs. This result suggests that upregulation of 12-LO by Ang II leads to the downregulation of CCL5 expression in SHR VSMCs.